The House of Representatives voted on Thursday to require the labeling of foods that contain genetically engineered ingredients, clearing the bill’s final obstacle before it heads to the White House, where President Obama is expected to sign it into law.

“Today’s vote is a resounding victory not only for consumers and common sense but also for the tremendous coalition of agricultural and food organizations that came together in unprecedented fashion to get this solution passed,” said Pamela G. Bailey, chief executive of the Grocery Manufacturers Association.

The long road to labeling foods with genetically engineered, or G.M.O., ingredients is drawing to a close after a battle that cost food and biotech companies hundreds of millions of dollars over the last few years. But the wrangling over how the language of the law will be interpreted and put into practice will probably go on for years.

“What today really means is that we’ve left the legislative period of this battle after seven years and moved into the regulatory and marketplace phase of it, which was where it was always headed anyway,” said Gary Hirshberg, a founder of Just Label It, a coalition that advocates labeling.

The Food and Drug Administration, for instance, has said the bill’s definition of which foods would require labeling would not include many products containing highly refined oil and sweeteners like canola oil or high-fructose corn syrup. After processing, such ingredients contain no genetic material that would identify them as coming from a genetically engineered source, which is what the bill requires.

The Agriculture Department, which will oversee G.M.O. labeling under the law, has disagreed with that interpretation, but many say the definition of what requires labeling and what does not will ultimately end up in court.

“A court interpreting the issues that will be raised in litigation — and there’s no question that there will be litigation — will look first and probably only to the language of the statute,” Senator Richard Blumenthal, Democrat of Connecticut, said at a news conference on labeling last week.

The bill allows companies several choices for labeling. They can add text to a label stating that it contains genetically engineered ingredients; put a symbol (yet to be determined) on packaging to denote such ingredients; or use a “digital link” like a quick response, or Q.R., code that consumers can scan with their smartphones.

Many proponents of G.M.O. labeling contend that anything short of text will allow food companies to obscure the genetically engineered ingredients in their packaging. They object in particular to Q.R. codes, which they consider discriminatory because many consumers do not have access to the tools needed to read them.

Senators supporting the measure have suggested that grocery stores will supply devices to help consumers navigate the codes, but there is no mention of that in the bill that Congress has passed.

“We don’t think the Q.R. code is a viable or even an honest disclosure,” Mr. Hirshberg said. “It’s just another way of keeping citizens in the dark — every 13-year-old knows Q.R. codes are dead.”

Many companies added language to their packaging to comply with a Vermont labeling law that went into effect on July 1. That requirement effectively established national labeling on many of the products in the average grocery store.

The federal law renders Vermont’s law and other state labeling laws null and void, but companies will have to weigh the expense of taking text off labels, not to mention the risk of irritating consumers interested in increasing transparency about the foods they eat. A survey of more than 1,500 consumers by Label Insight, a research firm whose clients include major food companies and grocery businesses, found that 37 percent of consumers said they would be willing to switch brands if another brand shared more detailed product information.

Additionally, Whole Foods Market, whose shelves are prized real estate among food manufacturers, will require labeling in two years.

And on Thursday, as the House was debating and voting on the labeling bill, Dannon announced that all its yogurt products in the United States would be labeled to disclose genetically engineered ingredients by the end of this year.

A version of this article appears in print on , on Page B2 of the New York edition with the headline: After Years in Dispute, G.M.O. Labeling Requirement Heads to Obama. Order Reprints | Today’s Paper | Subscribe